1. Field of the Invention
The present invention relates to carbonated solid or semi-solid food (e.g., gelatin, pudding, custard, yogurt) that can be eaten using a spoon or other utensil. The invention also relates to a method of carbonating an already formed food under mild conditions which do not destroy the solid or semi-solid properties of the gelled food, preferably yogurt.
2. Description of the Problem and Related Art
Presently carbonated semi-solid or solid foods (e.g. yogurt) are made by one or more complex processes in which the components (before mixing or fermentation) rather than the final product are carbonated. Some semi-solid foods can be carbonated in their final form, but carbonation using carbon dioxide requires additional production equipment. At the present, only liquids are carbonated using carbon dioxide in their final form. Therefore, the food industry does not yet produce carbonated semi-solid or solid foods in significant amounts. Consumer acceptance testing in this field demonstrates that such foods have the potential for successful commercialization.
A useful semi-solid or solid food (e.g. yogurt, custard, pudding, gelatin) product having desirable levels of carbonation has been elusive. Previous methods for carbonating yogurt include for example, adding carbonated water to a yogurt; manufacturing a liquid, drinkable yogurt by existing commercial processes for carbonating liquids; and a method for producing a powdered, drinkable liquid yogurt by adding metal carbonates to a powdered yogurt mix. Specific references are presented and discussed below.
None of the existing methods are suitable for making a highly viscous solid or semi-solid food product having the desired levels of carbonation. All of these processes result in either a product having sufficient levels of carbonation and low viscosity, or a product having the desired viscosity, but low levels of carbonation.
The previous processes do not teach one skilled in the art concerning how to select the temperature, pressure, surface area, agitation, etc. ranges which are best for carbonating semi-solid, solid, or otherwise highly viscous foods. No process has been disclosed which would allow manufacturers of dairy and other semi-solid or solid food products to use existing carbonation equipment or machinery with only slight modifications or additions.
The following patents and articles are of general and specific interest.
I. Rubenstein, in U.S. Pat. No. 3,503,757, discloses a method of making a frozen confection and in a treatment zone by contacting it with multiple finely divided streams of gaseous carbon dioxide followed by freezing the mix.
R. U. Schenk, in U.S. Pat. No. 4,206,224, discloses dry mix to be combined with water to produce a carbonated liquid yogurt.
J. D. Efstathiou et al., in U.S. Pat. No. 4,676,988, disclose the carbonation of milk to produce a low acid carbonated liquid milk product (a beverage).
S. H. Ahmad et al., in U.S. Pat. No. 4,804,552, disclose a method for carbonating a liquid dairy product. The liquid dairy product is heated at 160.degree. F. for up to 30 minutes to denature the protein present. This liquid is then treated with volumes of pressurized gaseous carbon dioxide.
S. H. Ahmad et al., in U.S. Pat. No. 4,919,960, disclose a process for making a carbonated liquid dairy product. The food is heated between 160.degree. F. and 200.degree. F. for 5 seconds to 30 min followed by gaseous carbon dioxide treatment.
R. Mack, in UK Patent 364,657, discloses a method for producing effervescent refreshing drinks using liquid milk. The carbon dioxide gas is bubbled through the milk.
UK Patent 1,005,399, assigned to American Machine and Foundry, discloses a method of enhancing flavor of chilled or frozen dairy desserts such as soft ice cream et al. by incorporation of controlled amounts of carbon dioxide, and also the unique products that result from the process. The level of carbon dioxide used is sufficient to lower the pH value of the mixture.
E. Yeghiaian, in Canadian Patent 1,143,111, discloses a formulation of a mixture of sour yogurt from cow's milk in water and carbonated to make new liquid beverage.
P. H. J. M. Evers, in European Patent Publication D117 011, discloses the introduction of gaseous carbon dioxide to a fermented milk such as yogurt to produce a beverage that can be stored for a long period of time.
M. A. Tracy, in World Patent Publication WO 89/02221, discloses the contacting of a carbon dioxide gas or a mixture of gases with a liquid milk product at a low temperature of less than 10.degree. C. and high pressure from 50 kpa to 200 kpa. The liquid carbonated milk product retains its carbonation until opened.
Soviet Union Patent SU 625 677, discloses a gassed whey drink prepared by heating, cooling, clarifying, flavoring and a specific two stage carbon dioxide treatment.
Japanese Patent Publication 51-022861, discloses a carbonic milk beverage which is fermented followed by addition of carbon dioxide.
Japanese Patent Publication 57-206 333, discloses a preparation for a thick liquid fermented milk containing carbon dioxide gas and nonfat milk solids.
Japanese Patent Publication 63-141544, discloses a process of carrying out the fermentation of a milk mix. The fermented milk contains carbon dioxide gas and has a mild and fresh taste and a smooth texture and improved storage at low temperature.
Japanese Patent Publication 63-263044, discloses a method of adding a gelling agent and bacteria to milk, fermenting the milk to a product having a carbon dioxide content 0.1 to 0.2 weight/volume percent.
Japanese Patent Publication 63-263045, disclose a milk fermented in a bed and homogenized in a chilled state. This product is mixed with aqueous pectin and carbon dioxide gas.
Japanese Patent 64-67150, discloses a process to combine carbon dioxide gas in milk, etc. in the presence of lactic acid to obtain a solid yogurt having a uniform level of carbon dioxide gas.
H. S. Choi et al., in Journal of Dairy Science, Vol. 68, pgs. 613-619, published in 1985, discloses a method of preparation of sweetened and plain carbonated yogurt beverages.
D. L. Barnes et al., in Cultured Dairy Products Journal, p. 21-25, published in August 1992, disclose the effect of buffering agents on a sweetened acidified carbonated milk liquid beverage.
None of these patents or publications individually or separately teach or suggest the present invention.
All patents, publications, articles, references, standards, and the like cited in this application are incorporated by reference in their entirety.
Based on the above discussion, it is apparent there remains a need for a new process to produce a solid or semi-solid spoonable food, e.g., yogurt, which is carbonated to high levels of carbon dioxide. Also, the food having the high level of carbon dioxide has special physical, chemical and taste properties. The presently claimed process and food product fulfills these needs.